Wiper blade cleaner for xerographic machines

ABSTRACT

Apparatus for cleaning dry residual toner from the photoconductive surface of a xerographic type copying machine for reuse. The apparatus comprises a wiper blade disposed across the path of operating movement of the photoconductive surface with the wiping edge thereof in physical contact therewith. The wiper blade is supported on a carriage movable in a direction generally longitudinal of the blade. A driver is provided to slowly oscillate the carriage together with the wiper blade back and forth to improve blade cleaning action and wear, and reduce the tendency for toner and other foreign matter to become trapped under the blade. A control means is provided to operate the carriage driver while the photoconductive surface is moving and thereafter up to a short interval.

United States Patent 1 Till [54] WIPER BLADE CLEANER FOR XEROGRAPHIC MACHINES [75] Inventor: Henry R. Till, Rochester, N.Y.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: May 13, 1971 [21] Appl. No.: 142,965

[52] US. Cl ..15/256.53, 355/15 [51] Int. Cl. ..G03g 15/00 [58] Field of Search...15/256.53, 256.51, 256.5, 308, 15/301; 355/15; 118/637, DIG. 23, 261' [111 3,724,020 [451 Apr. 3, 1973 Primary Examiner-Leon G. Machlin Attorney-James .l. Ralabate, Donald F. Daley and Frederick E. McMullen [57] ABSTRACT Apparatus for cleaning dry residual toner from the photoconductive surface of a xerographic type copying machine for reuse. The apparatus comprises a wiper blade disposed across the path of operating movement of the photoconductive surface with the wiping edge thereof in physical contact therewith. The wiper blade is supported on a carriage movable in a direction generally longitudinal of the blade. A driver is provided to slowly oscillate the carriage together with the wiper blade back and forth to improve blade cleaning action and wear, and reduce the tendency for toner and other foreign matter to become trapped under the blade. A control means is provided to operate the carriage driver while the photoconductive surface is moving and thereafter up to a short interval.

5 Claims, 6 Drawing Figures PATENTED APRB I973 SHEET 1 OF 4 AT TOR/VF) not PATENTEUAPRB 1975 3.724020 SET 3 BF 4 WIPER BLADE CLEANER FOR XEROGRAPHIC MACHINES This invention relates to an apparatus for cleaning the photoconductive surface of a xerographic type copying machine, and more particularly, to an improved wiper blade apparatus for cleaning toner from the photoconductive surface of a xerographic type copying machine.

In xerographic type copying machines, an electrostatic image of the document being copied is formed on a photoconductive surface, and that image is then developed with a suitable powdered material, conventionally called toner. The toner delineated image is thereafter transferred to the copy material, normally paper, which is then fixed to form the finished copy.

In machines of this type, the photoconductive surface is normally reused, and in preparation therefor, the surface is cleaned to remove vestiges of toner from the previous imaging cycle. While cleaning the photoconductive surface may be effected in a number of ways, one way is to wipe or scrape the photoconductive surface with a blade or wiper. This type of cleaning arrangement normally requires that the wiper blade be in physical contact with the moving photoconductive surface and as a result any defect, protrusion, scratch, or the like in the photoconductive surface may result in accelerated or uneven wear of the blade wiping edge with consequent deterioration in cleaning efficiency. As such uneven wear progresses, undesirable ghosting and streaking of the copy sheets may appear.

In addition, foreign matter and material, such as fiberous elements from the copy paper, plastic components in the machine, drive belts, and other sources may become lodged between the blade and the photoconductive surface. This may result in improper or incomplete cleaning of the photoconductive surface and streaking or marring of the copies.

It is a principal object of the present invention to provide a new and improved wiper blade cleaning apparatus for copying machines.

It is an object of the present invention to provide an improved oscillatory wiper blade cleaner for the photoconductive surface of a copying machine which slowly oscillateswhile the photoconductive surface is in use.

It is an object of the present invention to provide an improved wiper blade cleaner for the photoconductive surface of a xerographic type copying apparatus having reduced streaking tendencies.

It is an object of the present invention to provide a blade cleaner for scraping the photoconductive surface of a copying machine to remove residual dry toner material therefrom incorporating means to slowly move the blade back and forth across the photoconductive surface during operating movement thereof to prevent trapping of foreign material thereunder and enhance wear of the blade wiping surface.

It is an object of the present invention to provide an improved wiper blade apparatus for cleaning the xerographic drum of a copying machine having means to slowly oscillate the blade during movement of the drum to reduce localized wear on the blade that may result from drum imperfections and scratching, and reduce trapping of particulate matter between the blade and the drum surface.

This invention relates to a means for cleaning a repetitively movable xerographic surface in preparation for imaging thereon comprising, in combination: at least one blade-like element having a wiping edge adapted to bear against the xerographic surface, the blade being of sufiicient length to bridge substantially the entire imaging width of the xerographic surface; means supporting the blade with the blade wiping edge in operative contact with the xerographic surface so that during movement of the xerogra'phic surface, the blade wiping edge rides on the xerographic surface to clean the surface; means adapted when actuated to slowly oscillate the blade longitudinally and thereby move the blade back and forth across the xerographic surface; and control means responsive to movement of the xerographic surface to actuate the blade oscillating means whereby the contacting surface portions between the blade wiping edge and the xerographic surface are continually shifted during movement of the xerographic surface to improve wear on the blade wiping edge and cleaning of the xerographic surface by the blade.

Other objects and advantages will be apparent from the ensuing description and drawings in which:

FIG. 1 is a schematic view of an exemplary xerographic type copying machine incorporating the improved wiper blade cleaning apparatus of the present invention;

FIG. 2 is an enlarged side view with parts broken away showing details of the copying machine wiper blade cleaning apparatus and toner return mechanism;

FIG. 3 is an enlarged partial top view of the wiper cleaning apparatus and toner return mechanism shown in FIG. 2;

FIG. 4 is a cross-sectional view taken along lines 4- 4 of FIG. 3 showing details of the wiper blade cleaning apparatus of the present invention;

FIG. 5 is an enlarged view showing the driving mechanism for the wiper blade cleaning apparatus shown in FIG. 4; and

FIG. 6 is a schematic operating circuit for the wiper blade cleaning apparatus of the present invention.

Referring to the drawings, there is shown, for purposes of explanation, a xerographic type copying machine, designated generally by the numeral 10, incorporating the improved wiper blade cleaning apparatus of the present invention. Copying machine 10 has a drum-like part 11, the exterior surface 12 of which is finished with a suitable xerographic imaging or photoconductive material, in a manner known to those skilled in the art. Drum 11, which is suitably journaled by means of shaft 14, rotates in the direction indicated by the solid line arrow of FIG. 1 to bring the photoconductive surface 12 thereof past a plurality of xerographic processing stations as will appear more fully herein. Suitable drive means, represented herein by motor 101 (shown in FIG. 6) is provided to drive the various operating components of copying machine 10, there being suitable transmission means (not shown) to drivingly connect drum 11 with motor 101.

While a cylindrical or drum shaped photoconductive part 11 has been shown herein, other configurations,

such as a flat plate, belt, or the like may be contemplated.

The xerographic processing stations of copying machine include a charging station 15, wherein an electrostatic charge is deposited on the photoconductive surface 12 preparatory to imaging; an exposure station 16 where a light or radiation transmitted image of the document being copied is projected onto the photoconductive surface 12 to form a latent electrostatic image; a developing station 17 where a suitable xerographic developing material including ink or toner particles is cascaded onto the drum surface 12 to develop the latent electrostatic image on the drum surface; a transfer station 18 where the toner defined image is electrostatically transferred from the surface 12 of drum 11 to another surface, normally the copy sheet; and a drum cleaning and toner collecting station 19 where the surface of drum 11 is cleaned in preparation for reuse thereof.

Charging station includes a suitable corona generator 20, the discharge electrode or electrodes of which extend in spaced relation transversely across the drum surface in a direction generally parallel to the axis of drum 11. A suitable source of electrical energy is provided for corona generator 20 together with suitable shielding means to direct the charge emitted therefrom toward the drum surface.

Exposure station 16, which is downstream of charging station 15, has an image mirror 21 arranged opposite the surface 12 of drum 11 and adapted, via 'object mirror 22 and movable lens 24, to transmit an image of the document being copied onto the photoconductive surface 12 of the rotating drum 11 as the surface 12 moves therepast. The document being ry to drum 11. The portion of housing 28 forms a sump 29 within which a quantity of xerographic developing material is stored. A bucket type conveyor 30 is provided for bringing the developing material from the sump 29 to the drum surface 12, conveyor 30 serving at the discharge point thereof to cascade the developing material downwardly onto the upwardly moving photoconductive surface 12 of drum 11. As will be understood by those skilled in the art, the toner particles deposited onto the drum surface are electrostatically attracted thereto in a pattern complementary to the charge pattern on the photoconductive surface 12 to develop the xerographic image. Unused developing material falls back into the sump 29. Toner is supplied to sump 29 from plastic supply bottle 31 through an automatic dispensing apparatus 32. In addition, and as will appear more fully, toner removed from drum 11 at the toner cleaning and recovery station 19 is returned to sump 29.

Referring again to FIG. 1, image transfer station 18 is downstream of developer station 17. There, individual copy sheets drawn from either upper feed tray 35 or lower feed tray 36 are brought, by sheet feeding mechanism 37, into transfer relationship with the surface 12 of drum 11 where the developed image is electrostatically transferred from drum 11 to the copy sheet by means of transfer corotron 38 in a manner known to those skilled in the art. A stripper finger 39, operatively supported adjacent the surface 12 of drum 11 downstream of corotron 38, serves to remove or strip the copy sheet from drum 11 and onto vacuum transport 40. Transport 40 carries the image bearing copy sheet forward into the nip formed by fuser roll pair 41, 42. There a combination of heat and pressure functions to fix the toner image on the copy sheet as the sheet moves through the rotating fuser roll pair 41, 42 and into the sheet return track 44. Return track 44 includes pinch rolls 45 to carry the copy sheet to output tray 46.

A movable guide mechanism 47 is provided to allow the copy sheet to be alternately routed into the upper feed tray 35. From there, the copy sheet can be run back through the copying machine 10 to image the reverse side thereof following which the new image is fixed and the finished copy sheet having images on both sides discharged into output tray 46.

The drum cleaning and toner recovery station 19, which is downstream of the transfer station 18 and upstream of the charging station 15, serves to clean residual toner from the surface of drum 11 following image transfer. The removed toner is returned to sump 29 of developer housing 28 for reuse.

Referring particularly to FIGS. 2-4, toner cleaning and recovery station 19 includes a relatively soft, flexible wiper or cleaning blade 50. Blade 50, which as will appear, oscillates back and forth across drum 1 1 during cleaning, has a leading or wiping edge 52 in contact with drum surface 12. Since the normal imaging or working width of drum surface 12 is somewhat less than the overall width of drum 11, the effective length of blade 50 is preferably equal to the working width of drum surface 12 plus an amount equal to the stroke of blade movement to assure effective cleaning of the entire working width of drum 11. Blade 50 is preferably positioned so that wiping edge 52 thereof extends toward drum 11 in a direction opposite to the direction in which drum 11 rotates so that blade 50 in effect chisels toner from the drum surface. The relative angle between blade 50 and the plane tangent to drum 11 at the line of contact of the blade edge 52 with drum surface 12 is selected for optimum cleaning or scrapping efiect.

Blade 50 is comprised of any suitable flexible material, for example, polyurethene. Preferably, the blade material used should be relatively soft to prevent or minimize abrasion, scouring, scratching, etc. of the photoconductive surface 12 by the blade, y'et allow effective cleaning of the surface 12.

To return toner removed from drum 11 to developer sump 29, there is provided a transfer auger 60. Auger is carried on shaft 61 journaled in end caps 59, 59 of toner recovery housing 62. Suitable transmission means (not shown) are provided to drivingly interconnect gear'58 on auger shaft 61 with motor 101.

The lower portion of toner recovery housing 62, together with wiper blade 50, cooperate to form a channel-like recess 63 behind blade 50 into which toner removed by blade 50 deposits. Auger 60, which is operatively disposed within housing 62 adjacent recess- 63 conveys toner accumulating in recess 63 laterally along recess 63 to inlet 65 of toner conduit 70. There, bead chain conveyor 66 carries the toner through leg 70 of toner conduit 70 to developer sump 29.

A gear-like drive sprocket 68 is provided for bead chain conveyor 66, sprocket 68 being supported by stub shaft 69 rotatably joumaled in end cap 59' of toner recovery housing 62. Stub shaft 69 is conveniently driven from auger shaft 61 through suitable gearing means 67.

Leg 70 of toner conduit 70 leads from toner recovery housing 62 to sump 29 of developer housing 28, suitable openings 71 being provided in conduit 70 opposite sump 29 to enable the toner to be discharged therefrom. Toner conduit leg 70" leads back to housing 62 to complete the toner recovery loop. As will be understood, the relative interior and exterior dimensions of toner conduit 70 and conveyor 66 are chosen to assure efi'ective conveying of toner from recovery housing 62 through conduit 70 to developer sump 29.

To enchance the cleaning efficiency of wiper blade 50 and avoid or at least reduce localized wear on the blade wiping edge 52 and trapping of toner or other foreign material between blade 50 and the drum surface 12, the wiper blade 50 is slowly moved or oscillated back and forth across the drum surface whenever drum 11 is turning and up to a limited duration thereafter as will appear. Referring particularly to FIGS. 3-5 of the drawings, wiper blade 50 is supported on carriage 75 below and to one side of auger 60, carriage 75 having a longitudinally extending slot-like recess 76 therewithin for blade 50. Carriage 75 is in turn spring mounted on a movable support 79, adjustable mounting screw pair 78 being provided for this purpose. It is understood that the screw pair 78 permit the wiping edge 52 of blade 50 to be squared with the surface of drum 11. Support 79 is, in turn, slidably and pivotally mounted through ends 80 thereof on a transversely extending shaft 81 carried by end caps 59, 59 of toner recovery housing 62.

Support 79 includes a rearwardly projecting drive arm 83 to which bias link 84 is pinned. The opposite end of link 84 is attached through spring 85 to toner recovery housing 62. As will be understood, spring 85 serves to bias support 79 together with blade carriage 75 upwardly (clockwise as shown by the solid line arrow in FIG. 4) to hold the wiping edge 52 of blade 50 in operative contact with the surface 12 of drum ll. Suitable tension adjusting means in the form of screw 86 is preferably provided to enable the bias imposed by spring 85 to be regulated.

To move wiper blade 50 back and forth, motor 88 is provided. Motor 88 together with speed reducer 89 therefor are supported as a unit on toner recovery housing 62. Output shaft 87 of speed reducer 89 carries drive and control cams 90, 91 respectively thereon.

A cam follower 92 is provided for drive cam 90, follower 92 being pivotally secured to toner recovery housing 62 with follower arm 93 thereof riding on the peripheral surface of cam 90. The output arm 94 of follower 92 is drivingly connected through cross link 95 with drive arm 83 of housing 79. Preferably, a one-way coupling is provided between link 95 and arm 83, stop 96 on link 95 being relied upon to provide the requisite driving engagement therebetween on movement of link 95 in one direction (toward the left as shown in FIG.

6 5). Return spring 97, anchored between housing 62 and arm 83, serves to bias housing 79 in the opposite direction and maintain the several operating parts in driving contact with one another.

A control switch 98 is disposed adjacent control cam 91, arm 98 of switch 98 riding on the surface of cam 91. Referring particularly to FIG. 6, drive motor 101 is connected with a suitable source of electrical energy represented by leads L L through suitable switching arrangement shown here schematically as control switch 100. In the simplified schematic representation of FIG. 6, closure of switch 100 energizes motor 101 to operate the various components of copying machine 10, drum 1 1 rotating in the direction shown by the solid line arrow in FIG. 1 to move the drum photoconductive surface 12 past the various xerographic processing stations as described heretofore. Auger 62 which together with bead chain conveyor 66 are driven from motor 101, are also operated to return toner removed from the surface 12 of drum 11 through toner conduit to sump 29 of developer housing 28.

To control wiper blade motor 88, motor 88 is connected through contact 103 of control relay 103 across leads L L Blade control switch 98 parallels contact 103'.

With closure of control switch 100 and operation of motor 101, relay 103 is energized to close contact 103' thereof. Motor 88 is accordingly energized to move support 79 together with carriage and wiper blade 50 back and forth. With actuation of motor 88, control switch 98 is periodically opened and closed in accordance with the configuration of control cam 91 which, in the exemplary arrangement shown, comprises four times per cycle. It will be understood that the cyclic opening and closing of blade control switch 98 is without effect so long as contact 103 of control relay 103 remains closed. However, on opening of control switch 100, motor 101 and control relay 103 are deenergized. The operating components of copying machine 10 including drum 11 stop while deenergization of relay 103 opens relay contact 103. Blade control switch 98 accordingly becomes controlling to maintain motor 88 energized and blade 50 oscillating until opened by control cam 91. In the exemplary arrangement shown, this may extend up to one quarter cycle following stopping of drum 11. It is understood that where contact 103' and switch 98 open simultaneously, oscillation of wiper blade 50 terminates at the same time drum 11 stops and no carryover of blade oscillation occurs.

Motor 88 together with speed reducer 89 are chosen so as to move wiper blade 50 back and forth across drum 11 at a relatively slow speed, a speed of approximately 0.0125 inches per second having been found suitable. The effective stroke of cam and hence of blade 50 is approximately one-fourth inch; however, different stroke lengths may be contemplated, for example, one-half inch.

While the invention has been described with reference to the structure disclosed, it is not confined to the details set forth; but is intended to cover such modifications or changes as may come within the scope of the following claims. What is claimed is:

1. As a means for cleaning a repetitively movable xerographic surface in preparation for imaging thereon, the combination of:

at least one scraping blade having a wiping edge adapted to bear against said xerographic surface, said scraping blade being of sufficient length to bridge substantially the entire imaging width of said xerographic surface;

means supporting said scraping blade with said blade wiping edge in operative contact with said xerographic surface so that during movement of said xerographic surface, said scraping blade wiping edge rides on said xerographic surface to clean said surface;

means adapted when actuated to slowly oscillate said scraping blade longitudinally and thereby move said scraping blade back and forth across said xerographic surface; and

control means responsive to movement of said xerographic surface to actuate said scraping blade oscillating means whereby the contacting surface portions between said scraping blade wiping edge and said xerographic surface are continually shifted during movement of said xerographic surface to improve wear on said scraping blade wiping edge and cleaning and removing of leftover material from said xerographic surface by said scraping blade.

2. The cleaning means according to claim 1 in which said blade support means includes spring means for biasing said blade wiping edge into pressure contact with said xerographic surface.

3. The cleaning means according to claim 1 in which said blade supporting means includes a reciprocable blade carriage; said blade oscillating means including a rotatable cam-type driver, and

link means operatively connecting said cam driver with said carriage whereby rotation of said cam driver reciprocates said carriage together with said blade.

4. As a'means for cleaning a repetitively movable xerographic surface in preparation for imaging thereon, the combination of:

at least one blade-like element having a wiping edge adapted to bear against said xerographic surface, said blade being of sufficient length to bridge substantially the entire imaging width of said xerographic surface;

means including a reciprocable blade carriage supporting said blade with said blade wiping edge in operative contact with said xerographic surface so that during movement of said xerographic surface, said blade wiping edge rides on said xerographic surface to clean said surface; means adapted when actuated to slowly oscillate said blade longitudinally and thereby move said blade back and forth across said xerographic surface, said blade oscillating means including a rotatable cam-type driver and link means operatively connecting said cam driver with said carriage whereby rotation of said cam driver reciprocates said carriage together with said blade; said blade being supported by said carriage so that the wiping edge thereof projects outwardly therefrom; said blade supporting means including a carriage support shaft spaced opposite said xerographic surface and extending in a direction generally transverseto the direction of movement of said xerographic surface, said carriage being mounted on said shaft for reciprocating movement therealong by said driver and for swinging movement about the axis of said shaft; spring means tending to rotate said carriage in a predetermined direction about said shaft to hold the projecting wiping edge of said blade in contact with said xerographic surface; and

control means responsive to movement of said xerographic surface to actuate said blade oscillating means whereby the contacting surface portions between said blade wiping edge and said Xerographic surface are continually shifted during movement of said xerographic surface to improve wear on said blade wiping edge and cleaning of said xerographic surface by said blade.

5. In a wiper blade apparatus'for removing leftover toner from a recycling photoconductive surface in preparation for reuse thereof, the improvement comprising:

means for supporting said blade with the wiping edge thereof projecting toward said photoconductive surface in a direction opposite to the direction of movement of said photoconductive surface,

means biasing said blade wiping edge into contact with said photoconductive surface whereby said blade wiping edge works against the direction of movement of said photoconductive surface to chisel foreign material from said photoconductive surface and clean said photoconductive surface for reuse thereof; and I means adapted to oscillate said wiper blade backand forth across said photoconductive surface during cyclic operation of said surface whereby to reduce localized wear on the wiping edge of said wiper blade and enhance cleaning of said photoconductive surface by said blade. 

1. As a means for cleaning a repetitively movable xerographic surface in preparation for imaging thereon, the combination of: at least one scraping blade having a wiping edge adapted to bear against said xerographic surface, said scraping blade being of sufficient length to bridge substantially the entire imaging width of said xerographic surface; means supporting said scraping blade with said blade wiping edge in operative contact with said xerographic surface so that during movement of said xerographic surface, said scraping blade wiping edge rides on said xerographic surface to clean said surface; means adapted when actuated to slowly oscillate said scraping blade longitudinally and thereby move said scraping blade back and forth across said xerographic surface; and control means responsive to movement of said xerographic surface to actuate said scraping blade oscillating means whereby the contacting surface portions between said scraping blade wiping edge and said xerographic surface are continually shifted during movement of said xerographic surface to improve wear on said scraping blade wiping edge and cleaning and removing of leftover material from said xerographic surface by said scraping blade.
 2. The cleaning means according to claim 1 in which said blade support means includes spring means for biasing said blade wiping edge into pressure contact with said xerographic surface.
 3. The cleaning means according to claim 1 in which said blade supporting means includes a reciprocable blade carriage; said blade oscillating means including a rotatable cam-type driver, and link means operatively connecting said cam driver with said carriage whereby rotation of said cam driver reciprocates said carriage together with said blade.
 4. As a means for cleaning a repetitively movable xerographic surface in preparation for imaging thereon, the combination of: at least one blade-like element having a wiping edge adapted to bear against said xerographic surface, said blade being of sufficient length to bridge substantially the entire imaging width of said xerographic surface; means including a reciprocable blade carriage supporting said blade with said blade wiping edge in operative contact with said xerographic surface so that during movement of said xerographic surface, said blade wiping edge rides on said xerographic surface to clean said surface; means adapted when actuated to slowly oscillate said blade longitudinally and thereby move said blade back and forth across said xerographic surface, said blade oscillating means including a rotatable cam-type driver and link means operatively connecting said cam driver with said carriage whereby rotation of said cam driver reciprocates said carriage together with said blade; said blade being supported by said carriage so that the wiping edge thereof projects outwardly therefrom; said blade supporting means inclUding a carriage support shaft spaced opposite said xerographic surface and extending in a direction generally transverse to the direction of movement of said xerographic surface, said carriage being mounted on said shaft for reciprocating movement therealong by said driver and for swinging movement about the axis of said shaft; spring means tending to rotate said carriage in a predetermined direction about said shaft to hold the projecting wiping edge of said blade in contact with said xerographic surface; and control means responsive to movement of said xerographic surface to actuate said blade oscillating means whereby the contacting surface portions between said blade wiping edge and said xerographic surface are continually shifted during movement of said xerographic surface to improve wear on said blade wiping edge and cleaning of said xerographic surface by said blade.
 5. In a wiper blade apparatus for removing leftover toner from a recycling photoconductive surface in preparation for reuse thereof, the improvement comprising: means for supporting said blade with the wiping edge thereof projecting toward said photoconductive surface in a direction opposite to the direction of movement of said photoconductive surface, means biasing said blade wiping edge into contact with said photoconductive surface whereby said blade wiping edge works against the direction of movement of said photoconductive surface to chisel foreign material from said photoconductive surface and clean said photoconductive surface for reuse thereof; and means adapted to oscillate said wiper blade back and forth across said photoconductive surface during cyclic operation of said surface whereby to reduce localized wear on the wiping edge of said wiper blade and enhance cleaning of said photoconductive surface by said blade. 